Recently my kids and I were denied access to our flight because we missed the check in window. We were informed that new calculations would have had to have been made by the pilot, despite not having had any check in luggage. When are these calculations made? Before or after the passengers board? Apparently, our names did not make the manifest in time, despite nobody having boarded the plane yet. We were left stranded at the gate. Can anybody explain the procedures regarding these calculations, because I cannot understand why we were not permitted to fly?

  • $\begingroup$ What kind of plane was it? $\endgroup$ Commented Dec 3, 2014 at 22:17
  • $\begingroup$ Thanks for the responses... to put this simply, there were 5 of us in total who were denied the flight. $\endgroup$
    – Andy
    Commented Dec 4, 2014 at 0:12
  • $\begingroup$ Thanks for the responses... to put this simply, there were 5 of us in total who were denied the flight. Passenger A - 70kgs, Passenger B - 55kgs, Passenger C - 50kgs, Passenger D - 50kgs, Passenger E - 30kgs. Total 'carry on baggage' weight - 40kgs. Flight was Brisbane to Melbourne (2hrs 10mins). Aircraft type Airbus A320. I guess what i'm trying to determine is: Would there have been a significant alteration to the weight and balance calculations had these 5 passengers been permitted to fly? $\endgroup$
    – Andy
    Commented Dec 4, 2014 at 0:21
  • 1
    $\begingroup$ Probably not, but if something happened and it was discovered that the Captain allowed people to board AFTER the W&B was done, his ass would be grass. $\endgroup$ Commented Dec 4, 2014 at 0:42
  • 2
    $\begingroup$ Also, there may have been manifest issues. On a commercial plane you cannot fly unless your manifest is accurate and you can get in big trouble if you fly with a bad manifest. It is possible the airline's W&B system was tied to the manifest somehow, so if he updates the manifest, he HAS to recompute the W&B, which may require additional time. In this situation, the Captain may not want to change the manifest, just on time and scheduling considerations alone. $\endgroup$ Commented Dec 4, 2014 at 0:48

3 Answers 3


You're really asking two questions here

1) What is the procedure (ie when are the calculations made)?

2) Do additional passengers affect the weight?

What is the procedure

As soon as check in closes, the numbers for passengers and bags is finalized - nothing else can be added to the plane, otherwise it could potentially run out of fuel. Passengers can be removed, but the captain must be informed in case it affects balance.

At this point the captain calculates the required information for weight, fuel, and balance. It's done shortly after check in closes as there is a limited window in which to add extra fuel etc - remember that the tanker needs to be long clear before the engines can be started and other departure checklists can be run.

This is done so early because the pilot needs time to prepare the aircraft for departure, he doesn't have time to mess about later on adjusting the numbers, and if he has to re-calculate later it adds a whole extra area where mistakes can be made - especially since later on the pilot is likely to be more distracted. Doing it once is fairly easy, you plug the number of passengers into a set of sums along with temperature and other related factors, and it works fuel load out for you. If you try adding passengers you have to re-calculate this, then work out how much extra to add... it's just a whole bunch of extra things that can go wrong.

Do extra passengers affect the weight/balance of the aircraft

Short answer: yes

Take an A319 as an example aircraft: empty, it weighs 40,000 kg, up to a maximum of around 60,000kg

Now I have no idea what you and your family and bags weigh, but let's produce a range. Please don't be insulted by the range: the airline aren't judging your weight when deciding if you can board late: they have to have a single rule regardless of whether it's a skinny teenager travelling alone or a party of 15 obese people

  • You're an adult, so you presumably weigh anywhere between 50 and 150kg
  • You said children but don't state an age, so they could be newborns or adults: weight anywhere between 2kg and 150kg
  • I don't know how many children you have, but for the sake of argument I'll guess it's between 2 and 5 (as you said "children") - that's somewhere between 4 and 750kg

So your total weight for a single family is anywhere between 54kg and 900kg. Chances are most families are more like 250-300kg (a couple of adults at 60-100kg each, and a couple of kids at 20-40kg), but airlines have to assume worst case, otherwise their check in staff have the impossible job of deciding who's too fat to board late.

So take that worst-case scenario (6 obese people) and add a 7kg carry-on bag each, that's nearly 1000kg of weight which the pilot doesn't know on the plane. Or over 2% of the aircraft's empty weight and nearly 1.5% of the maximum takeoff weight. This is assuming they have no hold bags.

Even if your family only weighs 250kg between you and your bags, that's still nearly 0.5% of the aircraft's empty weight - a not insignificant number.

And finally you have to remember that by carrying the extra 0.5% of weight in people, the aircraft needs some extra fuel. And a bit more fuel to carry that extra fuel, and both of those extra amounts of fuel change the balance of the aircraft.

In most "normal" flights you aren't going to make a huge enough difference to balance to cause a crash, or change the fuel requirement enough to cause an issue, but if the aircraft had to divert, you could be the difference between running out of fuel or not, and in some worst-case circumstances a really big family could upset a small aircraft.

  • $\begingroup$ I doubt this is as much an issue on a 747 as it would be on a much smaller aircraft. $\endgroup$ Commented Dec 3, 2014 at 15:18
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    $\begingroup$ While a Captain may do the weight and balance on small aircraft, on large aircraft that function is handled by others. When I was flying Metroliners, I did it. When I was flying 747 passenger aircraft, dispatch handled that. When I was flying 747 freighters, the loadmaster assigned to the flight did it. $\endgroup$
    – Terry
    Commented Dec 3, 2014 at 19:01
  • $\begingroup$ @terry - that's certainly true in at least some cases: regardless, that person usually has other tasks and the airline doesn't want them having to do it again (usually with trickier sums), wasting time re-stowing and adding fuel etc just for a late running passenger $\endgroup$
    – Jon Story
    Commented Dec 3, 2014 at 20:06
  • $\begingroup$ This is a good answer, but it's missing a operational detail. When the flight plan is issued, the fuel needed is often based on having a completely full passenger load. In addition, each airline allows for LMC (last minute changes) to the final load. As long as the aircraft already has enough fuel for a full passenger load, accepting additional passengers late shouldn't require additional fuel uplift. $\endgroup$
    – ksea
    Commented Sep 3, 2018 at 0:28

The Advisory Circular "AIRCRAFT WEIGHT AND BALANCE CONTROL" (AC120-27E) describes one way in which passenger weights and baggage weights may be calculated by the airlines for various passenger populations, aircraft sizes and configurations, and season (summer or winter, because of the effects of density altitude).

What may have happened is that they had already calculated W&B for the flight, loaded a certain amount of fuel for the passenger and cargo weight, flight plan, and weather, and didn't want to (or couldn't) recalculate.

You didn't say what kind of aircraft you were flying on, but you should know that the smaller or lighter the airplane, the more sensitive it is to weight and balance. When I've flown on a Dash-8, a certain number of passengers had to be fore, abeam, and aft of the wing in order to maintain the center of gravity. On a larger aircraft such as a 747, there is more flexibility with W&B.

  • $\begingroup$ Although your first and second paragraph are spot on, the third is a misnomer - while it would certainly be more possible for an airline to allow passengers to board a larger aircraft late, in practice they all implement at least a "No boarding once the calculations are done" rule regardless of aircraft (and in most cases, they implement a "No boarding when check-in is closed rule) - simply to avoid employees making judgement calls on what counts as a "big enough for late boarding" aircraft $\endgroup$
    – Jon Story
    Commented Dec 3, 2014 at 17:02
  • $\begingroup$ OP wrote: "Apparently, our names did not make the manifest in time, despite nobody having boarded the plane yet." Maybe I interpreted this wrong, but I took it to mean that the they arrived at the gate before anyone had boarded and were denied boarding. As a former Global Services flier on UA, I never had a problem walking up to the gate and getting on any flight, even after the last pax had boarded. So I question "in practice they ALL implement..." (emphasis mine), since I have had first-hand experience with walking on. $\endgroup$
    – rbp
    Commented Dec 3, 2014 at 17:28
  • $\begingroup$ "On a 747, they don't really care where you sit." From my experience they might even on sizable plane. I was on pretty empty flight one time and bunch of us were instructed to change our seats after boarding (to the window seats at empty rows). Think it was 737 though. $\endgroup$
    – Rarst
    Commented Dec 3, 2014 at 17:28
  • $\begingroup$ @Rarst do you know for a fact that you were asked to move because of weight and balance, and not because of some other operation consideration? It could happen as well on any lightly loaded flight, so a nearly empty 737 on a short hop in good weather could be subject to W&B seat reassignement. $\endgroup$
    – rbp
    Commented Dec 3, 2014 at 17:31
  • $\begingroup$ @rbp I am not confident since I wasn't explicitly told the reason, but it looked like they were distributing people along the edges of plane (they did a pass of it, looked, then did another). $\endgroup$
    – Rarst
    Commented Dec 3, 2014 at 17:34

I was in aviation many years in 3 countries in Traffic/Dispatch/Load Control (weight&Balance).

As most say on here the smaller aeroplanes are more balance critical.

I used to take great pride in getting an aeroplane closed up and ready for push back on schedule. I also used to take great pride in getting late pax on board and still getting a schedule. The loadsheet has a box at the bottom labelled LMC. Last Minute Changes. There is a specific weight allowed, dependent on aircraft, acceptable without having to recalculate. But a competent loadsheet officer should be able to within a very short period.

Flying is not the pleasure it used to be, security has made it far more complex. I was denied boarding recently in Sofia, check in was just closing as I arrived and the last pax just going through security. The EasyJet aeroplane had not even taxied on to stand and it had a thirty minute turnround. I had no baggage. Imagine how angry I was, knowing the system, knowing that checking me in would make no difference to the departure. To have a check-in agent telling me the Captain had already completed pre-departure procedures and would not allow a late pax. It was absolute bull, despite how cross I was I knew it was pointless getting angry at check in but internally I was seething.

The next flight to MAN wasn't until the following day so it was either a hotel or flight to London and then train to MAN. Of course these cheap airlines do not give refunds or transfer so it was a new ticket at great expense. There-in lies the crux in my opinion. I would suggest that the executives at the head of companies such as EasyJet have the policy as a way to increase revenue. At small airports such as Sofia it takes hardly any time to pass through, security & immigration. Obviously the bigger the airport the more time it takes. Gone are the days when a breathless Pax Agent would arrive at the gate 10 minutes before push back saying, please can you get these late pax on?

  • $\begingroup$ Welcome to Aviation.SE! the first part of this answer sounds useful and would benefit if a bit more details could be added, the rest looks more like a rant and as such is not a good fit here. please consider improving your post. $\endgroup$
    – Federico
    Commented Jun 5, 2015 at 10:13

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